This invention relates to microcontact printing and more particularly to an elastomeric stamp that provides improved process performance when very small (micrometer or nanometer) printing features are desired.
Microcontact printing is a lithographic method employing an elastomeric stamp and applicable to a variety of ink/substrate combinations [1-4]. After inking, applying, and removing the stamp, the resulting pattern can act as an etch resist, deposition catalyst, or as a final pattern itself. Most notably, applications include low-cost or flexible semiconductors, low-cost or flexible displays, advanced engineered surfaces, and the biological devices.
Dimensional inaccuracies in a stamp or substrate limit the feasible feature scales in microcontact printing; even infinitesimal variations in the stamp thickness have been shown to impact contact area, contact pressure and feature collapse.
A variety of stamping methods and machines [5-8] have been documented in the prior art. However, none of these machines, nor prior research investigations in stamp and pattern transfer integrity [9-12], have accounted for the sensitivity of the process to errors in stamp, substrate, or superstrate dimensions.
Traditional microcontact printing stamps are made of polydimethylsiloxane (PDMS) by casting the PDMS over a patterned surface, for example a wafer patterned with photoresist. This process results in a stamp with features imparted on one side, which is then mounted to a machine using the backside of the stamp or used in manual application. The incompressible elastomeric body of these stamps can develop significant contact pressure when compressed between printing plates or printing rolls. At micrometer scale displacements sufficient pressure develops to collapse the features on the stamp, destroying the intended transfer pattern.
The present invention enables accurate pattern transfer in situations in which pattern integrity would be compromised in traditional stamps.